Working memory (WM) and cognitive flexibility are the two major components of executive function. Does working memory affect task shifting? This issue is still controversial. Some researchers had found that the switching cost was not affected by working memory, so working memory was not associated with cognitive flexibility. However, other researches had shown that working memory was closely related to task shifting and resource constraint of working memory was one of the main sources of switching cost. So far, most studies on the relationship between working memory and task switching have adopted the dual-task paradigm. The main reason of the contradictory results was that different investigators manipulated different components of working memory in the experiment. If the researchers increased the load on the central executive component of working memory in the experiment, it would have a significant impact on task switching.?On?the?contrary,?task?switching?cost?in?the?experiment would not be affected by working memory load when other components of WM are manipulated. To further test this hypothesis, a Digital Updating Task (DUT) was adapted into a Digital Alternate Comparison Task (DACT). The goal of the present study is to address the interaction between working memory and task shifting by using Digital Alternate Comparison Task (DACT). Fifty-six college students aged 18-24 were tested through the DACT. The task was divided into high working memory load and low working memory load. In the study phase, participants were presented with two or three initial items, one for each figure (hexagon, square or circle). Participants were instructed to memorize the number for each shape. Then, they would be displayed with a series of new items. For each new item participants had to compare the number for the same shape with initial item. Through the regulation of working memory load, observing the changing of switching cost under different working memory load level. According to previous researches on the correlation between working memory and task shifting. We hypothesized that the reaction time was longer under the switching condition and switching cost increased with the working memory load. The results showed that reaction time under switching condition was significantly higher than that under non-switching condition. The accuracy under switching condition was significantly lower than that under non-switching condition. This indicated that there was more significant accuracy and reaction time deficits under the switching condition. What's more, the reaction time in switching condition under high working memory load was significantly longer than that under low working memory load. The accuracy under high working memory load was significantly lower than that under low working memory load. And the switching cost under high working memory load was also significantly higher than that under low working memory load. This indicated that the switching cost increased along with working memory load. We discussed and analyzed the experimental?results?with?the?limited?theory?of?attention?resources?in?details. These?findings?suggested?that?switching?cost?existed?in?DACT.?The?bigger?the?working?memory load,?the?larger?the?shifting?cost?is.?That?is,?these?findings?further?confirmed?the?close?relationship between?working?memory?and?cognitive?flexibility.